The objective of the proposed work is to understand the critical biochemical steps in the mechanisms of transfection and transfection enhancement. Enhancement of transfection in B. subtilis bears similarities to the SOS repair process in E. coli in certain respects. It results in an increase in the effeciency of DNA rescue in transfectant cells and it is induced by ultra-violet light in a process that requires protein synthesis. A mutant has been isolated which is constituitive for the enhanced transfection. This mutation, the ten c gene, has been generally mapped on the genome and more precise mapping is in progress to define its position. In addition, alterations in protein patterns and nucleolytic activity associated with the ten c gene and a new class of transfection enhancement mutations which are non-inducible (ten) are under study. Analysis of mutants devective in DNA uptake which lack Mn2 plus stimulated deoxyribonuclease activity and show altered peptide patterns in two dimensional gel electrophoresis is planned. It is anticipated that identification of specific enzymes essential for processing events at the bacterial surface will permit their use in enzyme complementation studies of the transformation defective mutants and thus permit the construction of a detailed enzymatic pathway for the binding and entry of DNA in competent B subtilis.